ROOM_HEATER_CONTROL

Published:2009/7/8 1:57:00 Author:May | From:SeekIC

Use of phase control for triac provides gradual reduction in heater load current as desired temperature is approached, eliminating large overshoots. R2 is adjusted so al is of at desired temperature, turning Q2 off and preventing firing of triac. If temperature decreases, resistance of sensor RT increases and transistors initiate firing of triac.If RT continues to increase, C1 charges faster and triac is triggered earlier in each half-cycle, delivering more power to load. Dashed Iines indicate alternate connections for controlling motor with constant load such as blower motor. For cooling applications, interchange FIT and R2.- Circuit Applications for the Triac, Motorola, Phoenix, AZ, 1971, AN-466, p 9.



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